The order of stability for the conformations of n-butane among these is
`{:("anti" , I),("gauche" , II),("eclipsed (partial)" , III),("eclipsed (fully)" , IV):}`

Options

A. `I>II>III>IV`
B. `IV>III>II>I`
C. `III>II>I>IV`
D. `II>III>I>IV`

Explanation

To determine the order of stability for the conformations of n-butane, we will analyze the different conformations: anti, gauche, eclipsed (partial), and eclipsed (fully).

### Step-by-Step Solution:

1. **Identify the Conformations of n-butane**:
- n-butane has several conformations due to rotation around the carbon-carbon single bonds. The key conformations to consider are:
- Anti (staggered)
- Gauche (staggered)
- Eclipsed (partial)
- Eclipsed (fully)

2. **Draw the Anti Conformation**:
- In the anti conformation, the two bulky methyl (CH3) groups are opposite to each other. This configuration minimizes steric hindrance and torsional strain, making it the most stable conformation.

3. **Draw the Gauche Conformation**:
- In the gauche conformation, the two bulky methyl groups are adjacent to each other (60° dihedral angle). This conformation has some steric strain due to the proximity of the bulky groups, but it is more stable than the eclipsed conformations.

4. **Draw the Eclipsed (Partial) Conformation**:
- In the partial eclipsed conformation, one methyl group is eclipsed with a hydrogen atom. This configuration has more torsional strain than the gauche conformation but less than the fully eclipsed conformation.

5. **Draw the Eclipsed (Fully) Conformation**:
- In the fully eclipsed conformation, the two bulky methyl groups are directly overlapping (0° dihedral angle). This arrangement creates the highest steric strain and torsional strain, making it the least stable conformation.

6. **Rank the Stability**:
- Based on the analysis:
- Most stable: Anti (1)
- Next: Gauche (2)
- Then: Eclipsed (partial) (3)
- Least stable: Eclipsed (fully) (4)

### Final Order of Stability:
The order of stability for the conformations of n-butane is:
1. Anti (I)
2. Gauche (II)
3. Eclipsed (partial) (III)
4. Eclipsed (fully) (IV)